asylum vs shelter

asylum

noun
  • A place of safety or refuge. 

  • The protection, physical and legal, afforded by such a place (as, for example, for political refugees). 

shelter

noun
  • A refuge, haven or other cover or protection from something. 

  • An institution that provides temporary housing for homeless people, battered women, etc. 

verb
  • To take cover. 

  • To provide cover from damage or harassment; to shield; to protect. 

How often have the words asylum and shelter occurred in a corpus of books? (source: Google Ngram Viewer )